Chlorinated acylmethylene dithioles and their preparation



United States Patent 3,361,764 CHLORINATED ACYLMETHYLENE DITHIULES AND THEIR PREPARATION Erwin Klingsherg, Mountainside, N.J., assignor to American Cyanamid Company, Stamford, Conn., a corporation of Maine No Drawing. Filed Dec. 22, 1965, Ser. No. 515,746 4 Claims. (Cl. 260327) This invention relates to a novel class of dithiole compounds and to a method for preparing the same. More particularly it relates to chlorinated acylrnethylene dithioles especially acylmethylene 4-phenyl-1,2-dithioles, :substituted by a chlorine atom on a carbon atom alpha to the carbonyl group. These compounds are monochlorination products of acylmethylene dithioles of structure PhR fil rcm.

in which Ph is a phenyl group, and R and R are selected from the group consisting of hydrogen and phenyl. These compounds are characterized by absorption in the visible region of the spectrum and are useful as yellow colorants for thermoplastic materials.

The acylmethylene dithiole starting materials may be prepared by condensing a 4-phenyldithiolium salt with a dialkyl ketone or alkyl benzyl ketone and dehydrogenating as shown in Equations I-IV of the following diagram. Such preparations are fully described in applicants US. Patent, No. 3,211,749, issued Oct. 12, 1965 and also in his publication, I. Am. Chem. Soc. 85, 3244 (1963).

The compounds of this invention are prepared by chlorination of acylmethylene dithioles, as shown in Equations V and VI of the diagram.

lih

l v Chlorination (VI) Cnlorina tion (S 02012) ($01012) In these equations Ph represents phenyl and X represents an anion derived from a strong acid, such as sulfuric, hydrochloric, etc.

In accordance with the present invention the chlorination of the acylmethylene dithiole compound is carried out in a non-polar organic solvent inert to chlorinating ice agents and preferably of relatively low boiling point, such as dichloromethane, dichloroethane, chloroform, carbon tetrachloride, benzene or ethyl bromide. A mild chlorinating agent should be used, such as chlorine or preferably sulfuryl chloride. The product is isolated by evaporation and recrystallized from a suitable solvent, such as a low molecular weight aliphatic alcohol, hexane, etc.

The following examples are presented to illustrate the invention. Degrees of temperature are in centigrade.

Example 1.Prepw'ati0n of starting material, 4,6-epidithio-5-ph enyl-3,5-pentadien0ne-2 MOLE;

Example 2.-3-chlore-4,6-epidizhio-5-phenyl-3,5-hexadienone-Z A solution of 0.81 ml. (1.35 g.; 0.0100 mole) of sulfuryl chloride in 3-4 ml. of dichloromethane is added at 0 to a solution of 2.34 g. (0.0100 mole) of the compound of Example 1 in 35 ml. of dichloromethane. The resulting solution is left overnight at room temperature and then evaporated to give 2.65 g. (99%) of brown product, M.P. 97101. Crystallization from 100 ml. of hexane gives 1.70 g. (63%) of orange-yellow needles, M.P. 101-5 A second crystallization of the product raises the M.P. to 1089. Its absorptivity in the visible spectrum at 433 m,u=46.2 liters per gram centimeter. Its molar extinction coefiicient 5: 12,300.

Analysis.-Calcd. for C H ClOS C, 53.6; H, 3.4; Cl, 13.2; S, 23.8. Found: C, 53.9; H, 3.6; Cl, 12.8; S, 23.9.

Example 3.1-chl0ro-4,6-epidithio-1,3,5-triphenyl-3,5- hexadienone-Z To a solution of 1.93 g. (5.0 millimoles) of 4,6-epidithio-1,3,5-triphenyl-3,S-hexadienone-Z [Compound IVg of E. Klingsberg, I. Am. Chem. Soc. 83, 3246 (1963)] in 15 ml. of ice-cold dichloromethane is added 0.41 ml. (0.69 g., 5.1 millimoles) of sulfuryl chloride. The solution is left overnight at room temperature and then evaporated to give 2.05 g. (97%) of brown solid, M.P. -8". Methanol gives yellow crystals, M.P. -1; the product also crystallizes from hexane. Its absorption peak, A is at 445 mu. Its absorptivity at 445 m is 43.2 liters per gram centimeter. Its molar extinction coefiicient e: 18,200.

Analysis.Calcd. for C24H1qC1OS2I C, 68.4; H, 4.0; Cl, 8.4; S, 15.2. Found: C, 68.5; H, 4.1; Ci, 8.6; S, 14.7.

3 Example 4 .Ulility air yellow colorants for thermoplastics To 100 parts of comminuted rigid polyvinyl chloride is added 2 parts of a dibutyl tin bis mercaptide heat stabilizer and 0.25 part of 2-hydroxy-4-rnethoxybenzophenone, a light stabilizer. The Whole is milled on a 2-r0ll Thropp mill, one roll of which is steam-heated. When a workable molten mass is obtained, 1 part of the compound of Example 2 is added and the mill is run until all of the compound is in the plastic. The band is then cut at every pass for fifty or more passes until a uniformly yellow band is obtained. The mass is then compressionmolded to give a 50 mil yellow plaque. The compound of Example 3 is similarly useful.

I claim: 1. A compound of the structure Ph R H l I (WW where R is hydrogen, phenyl or chlorine, R is hydrogen or phenyl and R" is hydrogen or chlorine; one, and only one, of R and R" being chlorine.

2. The compound of claim 1 in which R is chlorine and R and R" are each hydrogen.

3. The compound of claim 1 in which R and R are each phenyl and R" is chlorine.

4. A process of preparing a compound of claim 1 comprising contacting an acylmethylene dithiole in a low boiling non-polar organic solvent inert to chlorination, with at least one molecular equivalent of sulfuryl chloride until formation of said compound is complete, and thereafter removing said solvent and recovering said compound.

References Cited UNITED STATES PATENTS 2,657,2l6 10/1953 Gaudin 260-327 JAMES A. PATTEN, Primary Examiner. 

1. A COMPOUND OF THE STRUCTURE 